TISSUE INDICATOR DETERMINATION

• US 20130172776A1
• Filed: 06/17/2011
• Published: 07/04/2013
• Est. Priority Date: 07/02/2010
• Status: Abandoned Application

• Current Assignee: ImpediMed Limited
• Original Assignee: ImpediMed Limited
• Inventors: Ziegelaar, Brian William, Gaw, Richelle
• Application Number:
  US13/806,869
• Publication Number:
  US 20130172776A1
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/4878 Evaluating oedema

Abstract

A method for use in analysing impedance measurements performed on a subject, the method including, in a processing system, determining at least one impedance value at at least one frequency, the at least one impedance value representing the impedance of a segment of the subject, determining a tissue impedance parameter value using the at least one impedance value and determining a tissue indicator based at least in part on the tissue impedance parameter value.

Claims

1. A method for use in analysing impedance measurements performed on a subject, the method including, in a processing system:

a) determining at least one impedance value at at least one frequency, the at least one impedance value representing the impedance of a segment of the subject;

b) determining a tissue impedance parameter value using the at least one impedance value; and

,

c) determining a tissue indicator based at least in part on the tissue impedance parameter value.

2. A method according to claim 1, wherein the tissue impedance parameter value is indicative of an impedance at a characteristic frequency.

3. A method according to claim 1, wherein the method includes:

a) determining a fluid level impedance parameter value using at least one impedance value; and

,

b) determining a fluid level indicator using at least one fluid level impedance value.

4. A method according to claim 3, wherein the at least one fluid level impedance parameter value is indicative of an impedance at zero frequency.

5. A method according to claim 1, wherein the method includes, in the processing system:

a) determining first and second impedance parameter values, the first and second impedance parameter values being at least one of tissue impedance parameter values and fluid level impedance parameter values; and

,

b) determining at least one of the tissue indicator and a fluid level indicator using the first and second impedance parameter values.

6. A method according to claim 5, wherein the first and second impedance parameter values are determined for first and second body segments, respectively.

7. A method according to claim 6, wherein the first and second body segments are affected and unaffected body segments.

8. A method according to claim 5, wherein at least one of the first and second impedance parameter values is a predicted impedance parameter value.

9. A method according to claim 8, wherein the predicted impedance parameter value is determined using at least one reference impedance parameter value derived from a reference normal population.

10. A method according to claim 9, wherein the reference normal population is selected based on at least one of:

a) body segment dominance;

b) differences in body segment types;

c) ethnicity;

d) age;

e) gender;

f) weight; and

,

g) height.

11. A method according to claim 5, wherein the method includes:

a) determining a ratio of the first and second impedance parameter values; and

,

b) using the ratio to determine at least one of the tissue indicator and a fluid level indicator.

12. A method according to claim 11, wherein the method includes, in the processing system, determining at least one of the tissue indicator and a fluid level indicator using the equation:

13. A method according to claim 12, wherein the method includes, in the processing system and for determining the tissue indicator, determining the impedance ratio using the equation:

14. A method according to claim 12, wherein the method includes, in the processing system and for determining the fluid level indicator, determining the impedance ratio using the equation:

15. A method according to claim 12, wherein the scaling factor is selected so that a threshold value indicative of at least one of a presence or absence of tissue fibrosis and a presence or absence of oedema is an integer value.

16. A method according to claim 1, wherein the tissue indicator is at least partially indicative of a presence, absence or degree of tissue fibrosis.

17. A method according to claim 1, wherein the method includes displaying a representation of at least one of the tissue indicator and a fluid level indicator.

18. A method according to claim 1, wherein the method includes in the processing system, causing one or more impedance measurements to be performed.

19. A method according to claim 1, wherein the method includes, in the processing system:

a) causing at least one excitation signal to be applied to the subject;

b) determining at least one signal measured across the subject; and

,

c) determining at least one impedance value using an indication of the excitation signal and the signal measured across the subject.

20. A method according to claim 1, wherein the method includes, in the processing system:

a) controlling a signal generator to thereby cause the at least one excitation signal to be applied to the subject; and

,

b) determining the at least one signal measured across the subject using a sensor.

21. A method according to claim 1, wherein the method includes using at least one of a tissue indicator and a fluid level indicator to diagnose a presence, absence or degree of tissue fibrosis.

22. A method according to claim 1, wherein the method includes determining an impedance parameter value from an impedance value measured at a single measurement frequency.

23. A method according to claim 22, wherein for a tissue impedance parameter value the measurement frequency is at least one of:

i) an intermediate frequency; and

,

ii) between 50 and 80 kHz.

24. A method according to claim 22, wherein for a fluid impedance parameter value the measurement frequency is at least one of:

i) a low frequency; and

,

ii) less than 50 kHz.

25. A method according to claim 1, wherein the method includes:

a) determining a number of impedance measurements, the number of impedance measurements including at least one impedance measurement at each of a number of measurement frequencies; and

,

b) determining the impedance parameter value using the number of impedance measurements.

26. Apparatus for use in analysing impedance measurements performed on a subject, the apparatus including a processing system for:

a) determining at least one impedance value at at least one frequency, the at least one impedance value representing the impedance of a segment of the subject;

b) determining a tissue impedance parameter value using the at least one impedance value; and

,

c) determining a tissue indicator based at least in part on the tissue impedance parameter value.

27. Apparatus according to claim 26, wherein the apparatus includes:

a) a signal generator for applying one or more electrical signals to the subject using a first set of electrodes;

b) a sensor for measuring electrical signals across a second set of electrodes applied to the subject; and

,

c) a controller for;

i) controlling the signal generator; and

,

ii) determining the indication of the measured electrical signals.

28. Apparatus according to claim 27, wherein the controller includes the processing system.

29. Apparatus according to claim 27, wherein the processing system includes the controller.

30. (canceled)